“Roundabouts have reduced traffic fatalities by 90% in Carmel,” said Brainard, a lawyer by training. “The U.S. average fatality rate per 100,000 people is 14. It tends to be higher in suburban areas because the roads are built wider for faster speeds. Indianapolis has done a little bit better than normal—11.7 per 100,000. The average in Carmel is two.”
https://www.carmel.in.gov/department-services/engineering/roundabouts